fix: replace null parents when resolving nested sections

lib/ini.js

@@ -190,7 +190,8 @@ const decode = (str, opt = {}) => {
       if (part === '__proto__') {
         continue
       }
-      if (!hasOwnProperty.call(p, part) || typeof p[part] !== 'object') {
+      // 2026-10-11: Null is a scalar value, so it cannot contain a nested section.
+      if (!hasOwnProperty.call(p, part) || p[part] === null || typeof p[part] !== 'object') {
         p[part] = Object.create(null)
       }
       p = p[part]

test/null-sections.js

@@ -0,0 +1,22 @@
+const ini = require('../')
+const t = require('tap')
+
+// 2026-10-11: Section paths replace null ancestors just like other scalar values.
+t.test('nested sections replace scalar parents', t => {
+  for (const value of ['null', 'false', 'text']) {
+    t.test(`replace a ${value} parent`, t => {
+      t.same(ini.parse(`a=${value}\n[a.b]\nx=1`), {
+        a: { b: { x: '1' } },
+      })
+      t.end()
+    })
+  }
+  t.same(ini.parse('[a]\nb=null\n[a.b.c]\nx=1'), {
+    a: { b: { c: { x: '1' } } },
+  }, 'replace a null parent inside a section')
+  t.same(ini.parse('a.b=null\n[a.b.c]\nx=1'), {
+    a: { b: { c: { x: '1' } } },
+  }, 'replace a null parent introduced by a dotted key')
+  t.same(ini.parse('a=null'), { a: null }, 'retain null without a nested section')
+  t.end()
+})